1. Field of the Invention
The present invention relates to a packing box suitable for packing a photosensitive recording material such as an X-ray film and, more specifically, a packing box for photosensitive recording material having a structure in which a lid member can be fitted easily to a box body while preventing the lid member from being fitted in a wrong way when fitting the lid member on the box body.
2. Description of the Related Art
In the related art, a packing box 101 including a box body 103 of a rectangular shape having a longitudinal direction and a short direction in cross-section for storing a photosensitive recording material and a lid member 105 provided at an output port for the photosensitive recording material so as to be capable of shielding light as separate members as shown in FIG. 9A has been used.
In such a configuration of the packing box in the related art, a lid-covered portion 107, which is configured so that the lid member 105 can be just-fitted, is formed on an upper portion of the box body 103, and the lid-covered portion 107 includes a lid-covered fixed surface 109 (the use of the parenthesis around the reference number 107 next to the reference number 109 in the drawings is used to indicate that the lid-covered portion 107 comprises the lid-covered fixed surface 109 extending in the longitudinal direction and a lid-covered rotatable portion 113 extending in the longitudinal direction in parallel with the lid-covered fixed surface 109 and being rotatable outward and downward along a valley bending line 111 to open the output port. Two lid-covered end surfaces 115, 117 are formed on both sides of the lid-covered fixed surface 109 at a right angle thereto so as to continue from the lid-covered fixed surface and the box body 103.
An upper corner portion 119 of the lid-covered rotatable portion 113 the use of the parenthesis around the reference number 107 next to the reference number 113 in the drawings is used to indicate that the lid-covered portion 107 comprises the lid-covered rotatable portion 113) on the side of the lid-covered end surface 115 is formed into an arcuate shape. As shown in FIG. 9B, a notched portion 121 notched in a hook shape is formed under the upper corner portion 119, so that a boundary portion between the upper corner portion 119 in the arcuate shape and the notched portion 121 has a pointed distal end portion 123. The configuration of the upper corner portion 119 and the distal end portion 123 as described above is formed by mountain folding along a perforated line 125 and a line 127 indicated by a dashed line in an extension plan view as shown in FIG. 9C.
However, the pointed distal end portion 123 as described above tends to be collapsed after opening and closing the lid member 105 many times. Once the distal end portion 123 is collapsed, a lower side 106 of the lid member 105 is caught by a portion indicated by a reference numeral 122 when closing the lid member 105 from then on, and hence the smooth closing operation may be hindered. In particular, the packing box for photosensitive recording material must be opened and closed in a dark room, an operator is obliged to close the lid member 105 depending only on a sense of his/her hands. Therefore, once the lid member 105 is caught, it is difficult to release the lid member 105 from the caught state only with the sense of operator's hands.
In addition, in the configuration in the related art as described above, there is no flap existing on the both sides of the lid-covered rotatable portion 113 as shown in FIG. 10A. Therefore, when an attempt is made to cover the lid member 105 in a state in which the lid-covered rotatable portion 113 is not closed completely as shown in FIG. 10B, a back plate 120 of the lid member 105 may be wedged between the lid-covered rotatable portion 113 and the two lid-covered end surfaces 115, 117. In a bright place, such a state can be recognized immediately. However, since the packing box for photosensitive recording material is required to be opened and closed in the dark room, it is possible that the operator takes out the packing box from the dark room without noticing that the box is in the state as described above, whereby the photosensitive recording material is exposed.